According to a feeding system of a double bus type, for example, as shown by FIG. 21, double busses X, Y are connected to a circuit breaker CB by way of bus side disconnecting switches DS1, DS2. The bus side disconnecting switches DS1, DS2 on a side of the circuit breaker CB as well as the circuit breaker CB on a side of the circuit breakers DS1, DS2 are connected to a grounding switch ES1. A current transformer CT1, a disconnecting switch DS3, a voltage transformer VT, a grounding switch ES2 and a line side grounding switch FES are connected between a cable head CHD constituting a connection end of a feeder cable and the circuit breaker CB. As shown by FIG. 22, the respective apparatus are insulated by a gas and connected to each other to constitute a gas insulated power apparatus integrated thereby.
In a background art, as shown by FIG. 22, the gas-insulated power apparatus is physically arranged with a gas-insulated main tank GIMT, a first gas-insulated branch pipe GTBT1, a second gas-insulated branch pipe GIBT2, a third gas-insulated branch pipe GIBT3, the double buses X, Y, the bus side disconnecting switches DS1, DS2, the circuit breaker CB, the grounding switch ES1, the cable head CHD, the current transformer CT1, the disconnecting switch DS3, the voltage transformer VT, the grounding switch ES2, and the line side grounding switch EFS and the like.
The second gas-insulated branch pipe GIBT2 connected with the Y bus is arranged right below the first gas-insulated branch pipe GIBT1 on the feeder side, and the third gas-insulated branch pipe GIBT3 connected with the X bus is arranged right below the second gas-insulated branch pipe GIBT2.
A case of a constitution shown in FIG. 22 poses a problem mentioned later, and therefore, there is a case of needing a constitution of FIG. 23. In FIG. 23, the third gas-insulated branch pipe GIBT3 is arranged on an opposed side of the first gas-insulated branch pipe GIBT1, and the second gas-insulated branch pipe GIBT2 having a length in an axial direction longer than the third gas-insulated branch pipe GIBT3 is arranged right below the third gas-insulated branch pipe GIBT3.
Further, the second and the third gas-insulated branch pipes GIBT2, GIBT3 are provided with peeping holes PWX, PWY in correspondence with respectives of the double busses X, Y, the bus side disconnecting switch DS1, DS2, the grounding switch ES1, and a length W2 of the second gas-insulated branch pipe GIBT2 having the longer length in the axial direction is set such that insides thereof can optically be recognized from the respective view ports PWX, PWY, particularly, the view port PWY on the second gas-insulated branch pipe GIBT2 does not overlap the third gas-insulated branch pipe GIBT3 in a vertical direction. Further, as a gas-insulated power apparatus having a structure in which there are not view ports PWX, PWY and the lengths in the axial direction of the second and the third gas-insulated branch pipes GIBT2, GIBT3 are substantially the same, there is JP-A-11-89028 (Patent Reference 1).
Further, as shown by FIG. 24, there is a case in which bus side current transformers CT21, CT22 are provided between the circuit breaker CB and the bus side disconnecting switches DS1, DS2 corresponding to the bus side disconnecting switches DS1, DS2 respectively, a physical arrangement thereof is as shown by FIG. 25, and the bus side transformers CT21, CT22 are arranged in the second and the third gas-insulated branch pipes CIBT2, GIBT3.
Patent Reference 1: JP-A-11-89028 (FIG. 1 and its explanation)